IJPL-214795 [mod-completion] (part) isApplicable handling in ModNavigatorTailType (sort of)

GitOrigin-RevId: 9acfd1878611b2a10caf057ff0d4ab981f43b5a6

java/java-impl/src/com/intellij/codeInsight/JavaTailTypes.java

@@ -1,7 +1,6 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInsight;
 
-import com.intellij.codeInsight.completion.InsertionContext;
 import com.intellij.codeInsight.completion.simple.BracesTailType;
 import com.intellij.codeInsight.completion.simple.ParenthesesTailType;
 import com.intellij.codeInsight.completion.simple.RParenthTailType;
@@ -125,29 +124,23 @@ public final class JavaTailTypes {
   };
   private static final String ARROW = " -> ";
   public static final ModNavigatorTailType CASE_ARROW = new ModNavigatorTailType() {
-    @Override
-    public int processTail(@NotNull Editor editor, int tailOffset) {
-      Document document = editor.getDocument();
-      document.insertString(tailOffset, ARROW);
-      return moveCaret(editor, tailOffset, ARROW.length());
-    }
-
     @Override
     public int processTail(@NotNull Project project, @NotNull ModNavigator navigator, int tailOffset) {
       Document document = navigator.getDocument();
+      if (!isApplicable(project, document, tailOffset)) return tailOffset;
       document.insertString(tailOffset, ARROW);
       return moveCaret(navigator, tailOffset, ARROW.length());
     }
 
-    @Override
-    public boolean isApplicable(@NotNull InsertionContext context) {
-      Document document = context.getDocument();
+    public boolean isApplicable(@NotNull Project project, @NotNull Document document, int tailOffset) {
       CharSequence chars = document.getCharsSequence();
-      int offset = CharArrayUtil.shiftForward(chars, context.getTailOffset(), " \n\t");
+      int offset = CharArrayUtil.shiftForward(chars, tailOffset, " \n\t");
       if (CharArrayUtil.regionMatches(chars, offset, "->")) {
         return false;
       }
-      PsiElement element = context.getFile().findElementAt(context.getStartOffset());
+      PsiFile file = PsiDocumentManager.getInstance(project).getPsiFile(document);
+      if (file == null) return false;
+      PsiElement element = file.findElementAt(tailOffset - 1);
       return PsiUtil.isJavaToken(element, JavaTokenType.DEFAULT_KEYWORD) ||
              PsiUtil.isJavaToken(element, JavaTokenType.CASE_KEYWORD) ||
              PsiTreeUtil.getParentOfType(element, PsiCaseLabelElementList.class) != null;

platform/analysis-api/api-dump-experimental.txt

@@ -1,3 +1,9 @@
+*a:com.intellij.codeInsight.ModNavigatorTailType
+- com.intellij.codeInsight.TailType
+- <init>():V
+- isApplicable(com.intellij.codeInsight.completion.InsertionContext):Z
+- processTail(com.intellij.openapi.editor.Editor,I):I
+- a:processTail(com.intellij.openapi.project.Project,com.intellij.openapi.editor.ModNavigator,I):I
 a:com.intellij.codeInsight.completion.CompletionService
 - *p:getVariantsFromGroupContributors(com.intellij.codeInsight.completion.CompletionParameters,com.intellij.codeInsight.completion.PrefixMatcher,com.intellij.util.Consumer):V
 *:com.intellij.codeInsight.completion.command.CommandCompletionFactory

platform/analysis-api/api-dump.txt

@@ -1,11 +1,6 @@
 c:com.intellij.codeInsight.CharTailType
 - com.intellij.codeInsight.ModNavigatorTailType
 - processTail(com.intellij.openapi.project.Project,com.intellij.openapi.editor.ModNavigator,I):I
-a:com.intellij.codeInsight.ModNavigatorTailType
-- com.intellij.codeInsight.TailType
-- <init>():V
-- processTail(com.intellij.openapi.editor.Editor,I):I
-- a:processTail(com.intellij.openapi.project.Project,com.intellij.openapi.editor.ModNavigator,I):I
 a:com.intellij.codeInsight.TailType
 - s:insertChar(com.intellij.openapi.editor.ModNavigator,I,C):I
 - s:insertChar(com.intellij.openapi.editor.ModNavigator,I,C,Z):I

platform/analysis-api/src/com/intellij/codeInsight/ModNavigatorTailType.java

@@ -1,9 +1,11 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInsight;
 
+import com.intellij.codeInsight.completion.InsertionContext;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.editor.ModNavigator;
 import com.intellij.openapi.project.Project;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Objects;
@@ -11,7 +13,23 @@ import java.util.Objects;
 /**
  * A base class for tail types that use {@link ModNavigator} instead of {@link Editor} to insert the tail.
  */
+@ApiStatus.Experimental
 public abstract class ModNavigatorTailType extends TailType {
+  /**
+   * @return true. {@link ModNavigatorTailType} should be always applicable. 
+   * @deprecated If you want to make it non-applicable, simply do nothing inside {@link #processTail(Project, ModNavigator, int)}.
+   * May become final in future.
+   */
+  @Deprecated
+  @Override
+  public boolean isApplicable(@NotNull InsertionContext context) {
+    return true;
+  }
+
+  /**
+   * @implSpec this implementation delegates to {@link #processTail(Project, ModNavigator, int)} adapting the arguments.
+   * Normally, it should not be overridden in clients.
+   */
   @Override
   public int processTail(final @NotNull Editor editor, int tailOffset) {
     return processTail(Objects.requireNonNull(editor.getProject()), editor.asModNavigator(), tailOffset);

platform/analysis-api/src/com/intellij/codeInsight/TailTypes.java

@@ -1,7 +1,6 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInsight;
 
-import com.intellij.codeInsight.completion.InsertionContext;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.editor.ModNavigator;
@@ -54,16 +53,15 @@ public final class TailTypes {
 
   private static final ModNavigatorTailType HUMBLE_SPACE_BEFORE_WORD = new CharTailType(' ', false) {
     @Override
-    public boolean isApplicable(@NotNull InsertionContext context) {
-      CharSequence text = context.getDocument().getCharsSequence();
-      int tail = context.getTailOffset();
-      if (text.length() > tail + 1 && text.charAt(tail) == ' ') {
-        char ch = text.charAt(tail + 1);
+    public int processTail(@NotNull Project project, @NotNull ModNavigator navigator, int tailOffset) {
+      CharSequence text = navigator.getDocument().getCharsSequence();
+      if (text.length() > tailOffset + 1 && text.charAt(tailOffset) == ' ') {
+        char ch = text.charAt(tailOffset + 1);
         if (ch == '@' || Character.isLetter(ch)) {
-          return false;
+          return tailOffset;
         }
       }
-      return super.isApplicable(context);
+      return super.processTail(project, navigator, tailOffset);
     }
 
     @Override